Modification of the catalytic properties of MoO2−x(OH)y dispersed on TiO2 by Pt and Cs additives

Addition of 5% Pt or alkali metals such as K or Cs each separately to the bifunctional MoO2−x(OH)y catalyst results in modification of the chemical structure of this system, especially in the case of alkali metals. A new MoO2−x(OA)y, AK, Cs, monofunctional structure having only metallic properties is formed. In the case of Cs for example, the MoOCs bond formation takes place in the course of the reduction process of MoO3 to MoO2 by hydrogen hinders the acidic BrØnsted MoOH formation, which usually is formed in this system. Characterization by surface XPS–UPS, ISS and FT-IR spectroscopic techniques as well as catalytic activity carried out at the same experimental conditions confirm the presence of this monofunctional MoO2−x(OCs)y system. On the contrary, platinum addition enhances the metallic character of the MoO2−x(OH)y bifunctional system in terms of slight improvement in the conversion of 1-heptene and n-heptane as well as dehydrogenation of methylcyclohexane to toluene.

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► Partial reduction by hydrogen of MoO3 deposited on TiO2 produces bifunctional MoO2−x(OH)y phase.
► Surface XPS–UPS, ISS and FT-IR techniques were employed to characterize this structure.
► Monofuctional (metallic) phase is obtained following Cs addition to MoO3.
► Catalytic reactions of 1-heptene, n-heptane and methylcyclohexane were carried out.